kindly answer both parts

A city consisting of 30 elementary schools was divided into 5 school districts numbered from 1 to 5. For the purpose of estimating the total students of elementary schools in the city, 2 school districts were selected using single stage sampling design. The sampling design is P((1,2)) =P((2,3)) = 2/7 P((2,5)) = P((1,3)) =P((2,4))= 1/7 (1) Calculate t, and t; (2) Suppose the school districts numbered 2, and 3 were actually selected using simple random sampling, resulting in the data shown in following table. Estimate total students of elementary schools in the city and its standard error. Sampled Number of schools Average students districts in the district per school 2 5 500 W 7 700